A 3D printer is a device, and method of using the device, to create a three-dimensional object from an electronic file that defines the shape of the object. 3D printers may be additive or subtractive in that they build up the object on a platform or build plate by adding material, or create the object by subtracting material. Most 3D printers are additive. Most milling machine and lathe operations are subtractive, for comparison. A typical additive 3D printer uses a head, also called an extruder or print head, which deposits small amounts of material at a time. The material may be liquefied in the head by heat, placed on the object being built, which then hardens as it cools. An alternative system uses a material that is hardened or polymerized by the use of light, UV light, other radiation or heat. Another alternative system uses a tank of liquid or gel, which is hardened point-by-point or piece-wise by the head.
A core unit of material in the object, or the definition of that unit in a source file, is often referred to as “voxel,” which corresponds roughly to volumetric pixel. A 3D source file may include vector or face definitions, rather than, or in supplement to, voxels. A 3D printer may convert some or all of a 3D source file to voxels, or it may convert the source data to a series of vectors, which are typically in a plane.
The prior art of 3D printers are based on an X-Y-Z, 3-axis, Cartesian, orthogonal grid. The X-Y axes usually define a horizontal plane, with the Z-axis being vertical. The object is formed in one X-Y plane at a time, with the Z-axis incrementing continually in steps. For each Z-axis increment, an X-Y plane is printed. The head in the X-Y plane may move in a repetitive scanning pattern, or in a series of vector motions, or both.
A characteristic of this design is that it requires three motors, effectively one for each of the X-Y-Z axes, not including a filament drive motor in the print head. The 3D printer is typically constructed in a box frame (a six-sided or five-sided frame enclosing the mechanisms and build surface), with each motion controlled by at least one screw drive or belt, and the build plate or its support moving on two orthogonal pairs of parallel slides. Alternatively, the head may move on the two orthogonal pairs of parallel slides with the platter fixed X-Y and moving vertically in the Z-axis. Thus, a typical design requires a box frame, 3 motors, 3 or more screws or belts, and four to six slides. Maintaining true orthogonality of the axes is a challenge. For some implementations, maintaining accuracy and linearity on one or more axes is also a challenge.
Prior art includes Fuse Deposit Modeling, or FDM™; FDM™ is a trademark of Stratasys, Inc. Prior art includes fused filament fabrication (FFF) and Plastic Jet Printing (PJP).
Prior art includes SCARA (Selective Compliance Robot Arm) arms, inverted SCARA arms, and robotic SCARA arms.
Embodiments of this invention include subtractive as well as additive manufacturing machines.